Autonomous transmit chain delay measurements

ABSTRACT

A system and method for determining transmission delay in a communications system. In some embodiments, satellite positioning information having System Frame Number (SFN) information may be received for a mobile device and observed time difference of arrival (OTDOA) measurements may be received for a mobile device. A location of the mobile device may be determined as a function of the received satellite positioning information. A Global Positioning System (GPS) time estimate may be determined as a function of the determined location of the mobile device. Transmission delay between a node serving the mobile device and an antenna serving the mobile device may be determined as a function of the received OTDOA measurements and determined GPS time estimate.

CROSS REFERENCES

The present applicationThis Reissue Application is a reissue ofapplication Ser. No. 15/242,272, filed Aug. 19, 2016, which issued asU.S. Pat. No. 9,778,371, and which is a divisional of U.S. applicationSer. No. 13/740,643, filed on Jan. 14, 2013, now U.S. Pat. No. 9,423,508and entitled “AUTONOMOUS TRANSMIT CHAIN DELAY MEASUREMENTS,” whichclaims the priority benefit of the provisional application entitled,“Autonomous Transmit Chain Delay Measurements,” Application Ser. No.61/585,681, filed on Jan. 12, 2012, wherein the contents of all of theforegoing applications are hereby incorporated by reference.

BACKGROUND

The location of a mobile, wireless or wired device is a useful andsometimes necessary part of many services. The precise methods used todetermine location are generally dependent on the type of access networkand the information that can be obtained from the device. For example,in wireless networks, a range of technologies may be applied forlocation determination, the most basic of which uses the location of theradio transmitter as an approximation.

Exemplary wireless networks may be a World Interoperability forMicrowave Access (“WiMAX”) network, a Long Term Evolution (“LTE”)network, and the like. Generally, WiMAX is intended to reduce thebarriers to widespread broadband access deployment withstandards-compliant wireless solutions engineered to deliver ubiquitousfixed and mobile services such as VoIP, messaging, video, streamingmedia, and other IP traffic. LTE is generally a 4G wireless technologyand is considered the next in line in the Global System for MobileCommunication (“GSM”) evolution path after Universal MobileTelecommunications System (“UMTS”)/High-Speed Downlink Packet Access(“HSPDA”) 3G technologies. LTE builds on the 3GPP family including GSM,General Packet Radio Service (“GPRS”), Enhanced Data Rate for GlobalEvolution (“EDGE”), Wideband Code Division Multiple Access (“WCDMA”),High Speed Packet Access (“HSPA”), etc., and is an all-IP standard likeWiMAX. LTE is based on orthogonal frequency division multiplexing(“OFDM”) Radio Access technology and multiple input multiple output(“MIMO”) antenna technology. LTE provides higher data transmission rateswhile efficiently utilizing the spectrum thereby supporting a multitudeof subscribers than is possible with pre-40 spectral frequencies. LTE isall-IP permitting applications such as real time voice, video, gaming,social networking and location-based services. LTE networks may alsoco-operate with circuit-switched legacy networks and result in aseamless network environment and signals may be exchanged betweentraditional networks, the new 40 network and the Internet seamlessly.While LTE protocol is being defined in the 3GPP standards as the nextgeneration mobile broadband technology, there is a need for mobilesubscriber or user equipment (“UE”) location in exemplary networks forcompliance with the FCC E-911 requirements and for other location basedservices. The 3GPP standards have also identified different methods thatcould be used for positioning of an UE for an evolved-UMTS TerrestrialRadio Access Network (“E-UTRAN”).

A number of applications currently exist within conventionalcommunication systems, such as those supporting OSM, Time DivisionMultiple Access (“TDMA”), Code Division Multiple Access (“CDMA”),Orthogonal Frequency Division Multiple Access (“OFDMA”) and UMTStechnologies, for which location solutions are needed by mobile units,mobile stations, UE or other devices and by other entities in a wirelessnetwork. Examples of such applications may include, but are not limitedto, GPS positioning and assisted global position system (“A-GPS”)positioning. A-GPS adaptable UE may acquire and measure signals from anumber of satellites to obtain an accurate estimate of the DE's currentgeographic position. GPS-based solutions may offer excellent accuracy,but GPS-based solutions generally suffer from yield issues in indoorenvironments or in environments that provide a poor line of sight to theopen sky in which to best receive GPS satellite transmissions.Furthermore, embedding GPS chipsets into UE may also add an associatedcost to the manufacturing of the UE and an associated cost to A-GPSfunctionality in the respective communications network. There, however,exists a need in the art to locate UMTS, OFDMA or W-CDMA mobile devicesto satisfy FCC E-911 regulations as well as to provide Location BasedServices for mobile phone users.

The 3GPP UMTS standard outlines several methods for location includingCell-ID, Enhanced Cell-ID (“E-CID”), A-GPS, Observed Time Difference ofArrival (“OTDOA”), and Uplink Time Difference of Arrival (“U-TDOA”).Cell-ID generally is the simplest method which provides coarsepositioning of mobile devices based on a known location of the coveragearea centroid of each base station sector. Additionally, A-GPS is astraightforward implementation for network and handset manufacturers dueto their legacy in CDMA2000 networks. Likewise, U-TDOA is also astraightforward technique for those skilled in the art and has beenwidely deployed for other air standards. OTDOA may be confronted withsignificant implementation challenges for network carriers, due to thefact that the base station timing relationships must be known, ormeasured, for this technique to be viable.

Some prior art systems are mobile appliance-based and determine theposition of the mobile appliance by receiving multiple dedicatedlocation signals either from components outside the mobile appliance'scommunication system, such as satellites and GPS systems or from anetwork of dedicated land-based antennas. Other prior art geolocationsystems that are network overlay, or infrastructure-based, systems usecombinations of specific, as opposed to ambiguous, measurementsgenerally from multiple base stations, such as AOA, TOA and TDOA. Thesespecific measurement values may be utilized to solve a set ofmathematical equations to determine the location of the mobileappliance.

There is, however, a need in the art to obviate the deficiencies in theprior art and provide methods that use uplink and/or downlink signalmeasurements in an exemplary communications network, such as, but notlimited to, a UMTS, an LTE network, etc. There is also a need in the artto provide the core measurements necessary for OTDOA positioning methodswhile attaining the accuracy standards that meet FCC Phase I and IIrequirements.

SUMMARY

Embodiments of the present subject matter may thus provide a system andmethod to autonomously measure signal delay in the transmission pathbetween a baseband processing unit and antenna. Hence, embodiments ofthe present subject matter may measure the transmission time of downlinksignals from the cell site antenna. Such an autonomous measuringtechnique may permit quick deployment of an exemplary OTDOA system forpositioning of a mobile device or UE.

In some embodiments of the present subject matter a method ofdetermining transmission delay in a communications system is provided.Satellite positioning information may be received for a mobile device,and E-CID positioning information received for the mobile device. Alocation of the mobile device may then be determined as a function ofthe received satellite positioning information. Transmission delaybetween a node serving the mobile device and an antenna serving themobile device may then be determined as a function of the received E-CIDpositioning information and the determined location of the mobiledevice.

In other embodiments of the present subject matter a method ofdetermining transmission delay in a communications network having aplurality of nodes is provided. The method may include receivingsatellite positioning information for a mobile device, the receivedsatellite positioning information including System Frame Number (SFN)information and receiving OTDOA measurements for a mobile device fromone or more of the plural nodes. A location of the mobile device may bedetermined as a function of the received satellite positioninginformation, and a Global Positioning System (GPS) time estimatedetermined as a function of the determined location of the mobiledevice. Transmission delay between a node serving the mobile device andan antenna serving the mobile device may then be determined as afunction of the received OTDOA measurements and determined GPS timeestimate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration of an exemplary architectural diagram forCoPL.

FIG. 1B is an illustration of the operation of an exemplary CoPLarchitecture.

FIG. 2A is an illustration of an exemplary architectural diagram forSUPL.

FIG. 2B is an illustration of the operation of an exemplary SUPLarchitecture.

FIG. 3 is an illustration of transmission delay measurement in someembodiments of the present subject matter.

FIG. 4 is diagram of network time boundary alignment for signalmeasurements according to some embodiments of the present subjectmatter.

FIG. 5 is a diagram of one embodiment of the present subject matter.

FIG. 6 is a diagram of another embodiment of the present subject matter.

DETAILED DESCRIPTION

With reference to the figures, where like elements have been given likenumerical designations to facilitate an understanding of the presentsubject matter, the various embodiments for autonomous transmit chaindelay measurements are described.

The following description of the present subject matter is provided asan enabling teaching of the present subject matter and its best,currently-known embodiment. Those skilled in the art will recognize thatmany changes can be made to the embodiments described herein while stillobtaining the beneficial results of the present subject matter. It willalso be apparent that some of the desired benefits of the presentsubject matter can be obtained by selecting some of the features of thepresent subject matter without utilizing other features. Accordingly,those who work in the art will recognize that many modifications andadaptations of the present subject matter are possible and may even bedesirable in certain circumstances and are part of the present subjectmatter. Thus, the following description is provided as illustrative ofthe principles of the present subject matter and not in limitationthereof. While the following exemplary discussion of embodiments of thepresent subject matter may be directed towards or references specifictelecommunications systems, it is to be understood that the discussionis not intended to limit the scope of the present subject matter in anyway and that the principles presented are equally applicable to othercommunications networks, systems and associated protocols.

Those skilled in the art will appreciate that many modifications to theexemplary embodiments described herein are possible without departingfrom the spirit and scope of the present subject matter. Thus, thedescription is not intended and should not be construed to be limited tothe examples given but should be granted the full breadth of protectionafforded by the appended claims and equivalents thereto. In addition, itis possible to use some of the features of the present subject matterwithout the corresponding use of the other features. Accordingly, theforegoing description of exemplary or illustrative embodiments isprovided for the purpose of illustrating the principles of the presentsubject matter and not in limitation thereof and may includemodification thereto and permutations thereof. The terms “device,”“handset,” “terminal,” and “station” are utilized interchangeablythrough the present disclosure and such use is not intended to limit thescope of the claims appended herewith. It should also be noted that theterms “node(s)” and “site(s)” and “station(s)” are also utilizedinterchangeably through the present disclosure and such use is notintended to limit the scope of the claims appended herewith.

Generally, LCS methods are accomplished through Control Plane (“CoP”) orUser Plane (“UP”) methods. CoP Location (“CoPL”) refers to using thecontrol signaling channel within the network to provide locationinformation of the subscriber or UE. UP Location (“UPL”), such as SecureUser Plane Location (“SUPL”) uses the user data channel to providelocation information. CoPL location approaches include, but are notlimited to, Angle-of-Arrival (“AOA”), ObservedTime-Difference-of-Arrival (“OTDOA”), Observed-Time-Difference (“OTD”),Enhanced-OTD (“E-OTD”), Enhanced Cell-ID (“E-CID”), A-GPS, and A-GNSS.UPL approaches include, but are not limited to, A-GPS, A-GNS S, andE-CID, where this position data is communicated over IP.

There are two established architectures associated with locationdetermination in modem cellular networks. These architectures are CoPand UP architectures. Typically, location requests are sent to a networkthrough a query gateway function, and depending on the networkimplementation, CoP or UP may be used. The difference between user planeand control plane, generally, is that the former uses the communicationbearer established with the device in order to communicate measurements.The latter uses the native signaling channels supported by thecontrolling network elements of the core and access to communicatemeasurements. For example, a CoPL solution supporting A-GPS would useits control plane signaling interfaces to communicate GPS data to/fromthe handset. Similarly UPL can conduct E-OTD, i.e., the handset takesthe timing measurements but it communicates them to the locationplatform using the data bearer. UPL has the advantage of not dependingon specific access technology to communicate measurement information.CoPL has the advantage that it can access and communicate measurementswhich may not be available to the device. Current models generallyrequire network operators to deploy one or the other, CoPL or UPL. CoPLgenerally uses the native signaling plane of the network to establishsessions and communicate messages associated with location requests andto communicate measurements used for determining location. The controlplane is the signaling infrastructure used for procedures such as callcontrol, hand-off, registration, and authentication in a mobile network;CoPL uses this same infrastructure for performing location procedures.CoPL can utilize measurements made by both the control plane networkelements as well as the end-user device being located.

FIG. 1A illustrates an exemplary architectural diagram of CoPL. A mobilestation or mobile appliance 101 communicates with an E-NodeB 105 viawireless interface LTE-Uu. A mobility management entity (“MME”) 113coordinates between the mobile appliance communication network and agateway mobile location center (“GMLC”) 117. In operation, a locationmeasurement device (not shown) may be connected to the E-NodeB 105 andmake measurements on the RF signals of the LTE-Uu interface, along withother measurements to support one or more of the position methodsassociated with the CoPL. Measurements from the location measurementunits are sent to a serving mobile location center (“SMLC”) orEvolved-SMLC (“E-SMLC”) 109 where the location of a mobile appliance/UE101 can be determined. The GMLC 117 may be connected to a homesubscriber server (“HSS”) 111 over an SLh interface.

The operation of a CoPL architecture is shown in FIG. 1B. This shows the3GPP location services architecture. A gateway mobile location centre(“GMLC”) 117 may be the network element that receives the locationrequests. The GMLC queries the HLR/HSS 111 over the Lh/SLh interface tofind out which part of the access network 107 is currently serving thetarget device. The GMLC 117 sends a location request to the currentserving core network node 113 via the Lg/SLg interface. The currentserving core network node 113 (e.g., MME) then passes the request to thepart of the access network 107 attached to the target device (e.g.,GERAN BSC, UTRAN RNC or E-UTRAN RNC). This access network element 107then invokes the facilities of the SMLC/SAS/E-SMLC 109. The locationrequest session between the access network node 107 and theSMLC/SAS/E-SMLC 109 provides a channel by which the SMLC/SAS/E-SMLC 109can ask for network measurements or to send messages to the end-userdevice 101 so that device measurement information can be exchanged. TheSMLC/SAS/E-SMLC 109 may also obtain location measurement informationfrom external devices 110 such as location measurement units (“LMUs”)which take RF readings from the air interface. Similarly, the device mayalso take measurements from external systems, such as GPS satellites,and communicate these to the SMLC/SAS/E-SMLC 109.

The E-SMLC may generally be a serving location node defined by 3GPP andis analogous to the GERAN-SMLC and UTRAN-SAS. The E-SMLC hosts positioncalculation functions and may be responsible for the overallcoordination of a location request including selecting appropriatepositioning technologies based on the requested quality of service(accuracy, response time), interacting with the mobile appliance andaccess network to serve assistance data and obtain appliance and networkbased measurements, providing the position calculation function,fallback positioning in case the primary location technique of choicefails, and generally assuring that a location result may be providedback to the tasking entity. Thus, the E-SMLC may generally support theinterface to the MME in accordance with 3GPP protocol specifications,support multiple positioning technologies including Cell ID, E-CID,handset-based and handset-assisted A-GPS/A-GNSS, OTDOA, uplink timingLMU technology, AOA, and hybrid positioning in accordance with emergingstandards and the demands of the market.

Developed as an alternative to CoPL, SUPL may generally be a set ofstandards managed by the Open Mobile Alliance (“OMA”) to transferassistance data and positioning data over IP to aid network andterminal-based positioning technologies in ascertaining the position ofa SUPL Enabled Terminal (“SET”). UPL does not explicitly utilize thecontrol plane infrastructure. Instead, UPL assumes that a data bearerplane may be available between the location platform and the end-userdevice. That is, a control plane infrastructure may have been involvedin establishing the data bearer so that communication can occur with thedevice but no location-specific procedural signaling occurs over thecontrol plane. As such, UPL may be limited to obtaining measurementsdirectly from the end-user device itself.

SUPL includes a Lup reference point, the interface between the SUPLLocation Platform (“SLP”) and SET, as well as security, authentication,authorization, charging functions, roaming, and privacy functions. Fordetermining position, SUPL generally implements A-GPS, A-GNSS, orsimilar technology to communicate location data to a designated networknode over IP. FIG. 2A illustrates an exemplary architectural diagram forSUPL. The illustrated entities represent a group of functions, and notnecessarily separate physical devices. In the SUPL architecture, an SLP201 and SET 207 are provided. The SLP 201 may include a SUPL LocationCenter (“SLC”) 203 and a SUPL Positioning Center (“SPC”) 205. The SLCand SPC may optionally communicate over the Lip interface, for instance,when the SLC and SPC are deployed as separate entities. The SET 207generally includes a mobile location services (“MLS”) application, anapplication which requests and consumes location information, or a SUPLAgent, a service access point which accesses the network resources toobtain location information.

For any SET, an SLP 201 may perform the role of the home SLP (“H-SLP”),visited SLP (“V-SLP”) or emergency SLP (“E-SLP”). An H-SLP for a SETincludes the subscription, authentication, and privacy related data forthe SET and may generally be associated with a part of the SET's homepublic land mobile network (“PLMN”). A V-SLP for a SET may be an SLPselected by an H-SLP or E-SLP to assist in positioning thereof and maybe associated with or contained in the PLMN serving the SET. The E-SLPmay perform positioning in association with emergency services initiatedby the SET. The SLC 203 coordinates operations of SUPL in the networkand interacts with the SET over the User Plane bearer to perform variousfunctions including, but not limited to, privacy, initiation, security,roaming, charging, service management, and positioning calculation. TheSPC 205 supports various functions including, but not limited to,security, assistance delivery, reference retrieval, and positioningcalculation.

SUPL session initiation may be network-initiated or SET-initiated. TheSUPL architecture provides various alternatives for initiating andfacilitating SUPL functions. For example, a SUPL Initiation Function(“SIF”) may optionally be initiated using a Wireless ApplicationProtocol Push Proxy Gateway (“WAP PPG”) 211, a Short Message ServiceCenter (“SMSC/MC”) 213, or a User Datagram Protocol/Internet Protocol(“UDP/IP”) 215 core, which forms user plane bearer 220. The operation ofUPL is shown in FIG. 2B. Secure User Plane Location is a standardspecification for UPL. Location requests come to the SLP 201 fromexternal applications or from the end-user device itself. If a datasession does not exist between the SLP 201 and the device 207 already,then the SLP 201 may initiate a request such that an IP session (userplane bearer is established between the device 207 and the SLP 201. Fromthen on, the SLP 201 may request measurement information from the device207. The device may also take measurements from the network 107 or fromexternal systems such as GPS 210. Because there may be no control planeconnectivity to the network, the SLP 201 cannot directly request anymeasurement information from the network 107 itself. More information onSUPL, including the Secure User Plane Location Architecturedocumentation (OMA-AD-SUPL), can be readily obtained through OMA.

Exemplary downlink positioning techniques and E-CID positioningtechniques have been identified as candidates for UE positioningtechnology for E-UTRAN access. For example, in a downlink positioningtechnique, the position of a UE may be estimated based upon measurementstaken at the UE of downlink radio signals from multiple nodes (e.g.,eNodeBs, etc.), along with the knowledge of the geographical coordinatesof the measured nodes and their relative downlink timing. In an E-CIDpositioning technique, knowledge of geographical coordinates of theserving node and additional UE/E-UTRAN radio resource measurements maybe employed to estimate the position of a UE. Embodiments of the presentsubject matter may thus obtain an estimated position of a UE bycombining measurements obtained from an exemplary E-CID process andmeasurements obtained from an exemplary OTDOA process.

3GPP standards have defined the downlink System Frame Number (SFN)initialization time to determine an absolute time of downlinktransmission. For example, an SMLC, E-SMLC, or equivalent may receiveOTDOA cell information from both the serving and/or reference eNodeB(s)that contain the SFN initialization time. This SFN initialization timemay be employed to determine an absolute downlink transmission time of adownlink frame at a cell site antenna by measuring the delay between thetime stamping module at the baseband and the transmission antenna.

A downlink SFN initialization time tagging mechanism, however, may occurin the eNodeB. Thus, in many deployment scenarios there may exist adelay in the transmission path between the eNodeB and the cell siteantenna due to cables, filters, and/or other passive or activecomponents. Further, such delays in the transmission signal path mayalso vary among different deployed sites. Transmission time of adownlink Frame Tx_enb_(i) at the Tx antenna of an nth eNodeB may beprovided by the following relationship:Tx_enb_(i)=SFN_(i)+δ_(i)  (1)where SFN_(i) represents the SFN initialization time at the n^(th)eNodeB and may be reported under assistance information from the i^(th)eNodeB under the OTDOA cell info Information Element (IE), and δ_(i)represents the delay at the i^(th) base station between the respectivetime stamping module and the transmission cell site antenna.

Exemplary embodiments may determine the delay in the transmission pathby using A-GNSS or A-GPS capable UEs, SETs or other mobile devices. Ofcourse, A-GNSS and A-GPS are provided as non-limiting examples, asembodiments of the present subject matter may include other exemplarysatellite systems such as, but not limited to, GLONASS, Galileo,Compass, BeiDou and the like.

For example, in one embodiment an E-SMLC or equivalent may initiatenetwork assisted GNSS positioning procedures and/or an E-CID procedureto obtain measurements from the UE associated with the procedure. Adelay in the transmission path may be determined based upon TimingAdvance (TA) measurements from the E-CID procedure and/or a targetlocation determined from any A-GNSS measurements. Thus, to determine thetransmission path delay, the UE(s) position(s) determined by or at theE-SMLC may be paired or associated with respective TA measurements forthe UE(s) obtained from the E-CID procedure.

In this embodiment of the present subject matter, both A-GPS/GNSS andE-CID positioning may be invoked from the E-SMLC or SLP. In oneembodiment, E-CID positioning may be invoked through the control planeto provide better accuracy, and/or A-GPS/GNSS positioning may be invokedthrough the SLP to minimize messaging overhead in the control plane. Ofcourse, embodiments of the present subject matter should not be solimited as both the control and user planes may be utilized inembodiments of the present subject matter.

If the position of the UE is determined using an exemplary A-GPS/GNSSpositioning method, then the TA received using E-CID may be employed toestimate the delay occurring in the transmission path or of the eNodeBas illustrated in FIG. 3. Further information regarding TA is providedin 3GPP TS 36.214, the entirety of which is incorporated herein byreference. With reference to FIG. 3, using an exemplary uplink E-CIDpositioning method where measurements may be obtained by the eNodeB 310,an E-SMLC may receive measurement results from the serving eNodeB 310containing TA for a target UE 320 as illustrated in Figure Ia. Asdescribed in 3GPP TS 36.455, the entirety of which is incorporatedherein by reference, two types of TA information may be available fromeNodeBs. According to 3GPP TS 36.214, TA may be determined at thetransmission/receiver (Tx/Rx) antenna connector point of the eNodeB. TheTA may account for both the propagation path delay and Rx/Tx path delay.Hence, if one assumes that the delay in the Tx and/or Rx path (i.e., the“transmission” path), 8, between the cell site antenna 330 and eNodeB310 are both equal, then the following relationship may be obtained:T_(ADV_type1)=2*(τ+δ)  (2)where, τ represents the propagation delay. Equation (2) may then berearranged to provide the transmission delay as:δ=(T_(ADV_type1))/2−τ  (3)

It should be noted that the asymmetry of delay in the Tx and Rx path dueto different size of filters in the RF front end may impact the actualdelay but should not impact the relative timing of downlink signals asthese asymmetries between the Tx and Rx path or chain may not varysignificantly from one base station to the other. Further, inembodiments where an SLP invokes an E-CID positioning procedure,T_(ADV_type1) may be replaced by the TA received from a SET within anLTE LID.

The propagation delay τ between the cell site antenna 330 and UE 320 maybe determined using knowledge of the position of the UE 320 and thelocation of the cell site; hence, an A-GPS/A-GNSS capable UE 320 may beused to determine the location of the UE 320. In the absence of TA Type1, TA Type 2 may also be used. In this embodiment, the transmissiondelay may be determined using the following relationship:δ=½(T_(ADV_type2))−τ  (4)

When an E-SMLC, SLP, or other management server or entity desires tocharacterize the delay in the transmission path or chain for aparticular site, a number of GPS/GNSS capable UEs served by that cellmay be selected. Thus, the E-SMLC or SLP may invoke A-GNSS and E-CIDpositioning procedures on the UEs and may retrieve positioningmeasurements from UE as outlined in 3GPP TS 36.305, 3GPP TS 36.455, and3GPP TS 36.355, the entirety of each being incorporated herein byreference.

In another embodiment, a delay in the transmission path may bedetermined from measurements obtained from the A-GNSS positioningprocedures and the SFN. Thus, the E-SMLC or equivalent may request theUE to report a GNSS-network-time association when returning A-GNSSsignal measurement information. In this embodiment of the presentsubject matter, an A-GPS/A-GNSS positioning method may be invoked by theE-SMLC or SLP, and the E-SMLC or SLP may receive OTDOA cell informationfrom the serving cell of the UE.

When initiating the A-GNSS method, an exemplary E-SMLC may request thetarget UE to report GNSS-network time association. ThefineTimeAssistanceMeasReq field may be set as TRUE under the IEGNSS-PositioningInstructions as discussed in 3GPP TS 36.355, theentirety of which is incorporated herein by reference. It should benoted that, while not required, the UE may support fine time assistancemeasurements, as indicated by the field fta-MeasSupport, in the IEA-GNSS-Provide-Capabilities.

When the E-SMLC indicates fineTimeAssistanceMeasReq, then the UE mayalign the measurement point with a cellular frame boundary and includethe same in the network time (e.g., SFN) so that the GNSS time reportedmay be the time occurs at the frame boundary. FIG. 4 provides anillustration of such an embodiment. With reference to FIG. 4, precisetime may be available after position determination, so the E-SMLC mayestablish the final GNSS-network time relationship. From the positioningdetermination of the UE, precise GNSS/GPS time of the SFN boundaryobserved at the UE may be determined. Assuming that the determinedGNSS/GPS time of SFN_(n) observed at the UE is UERx^(Nth) _(SFN), onemay determine the propagation delay τ from the cell site antenna to theUE as a function of the determined location of the UE and the cell sitelocation. If transmission time of the downlink frame N from the i^(th)base station cell site antenna is represented as Tx_eNB_(i) ^(Nth SFN),where i represents the serving base station, the following relationshipmay be obtained:Tx_eNB_(i) ^(Nth SFN)=UERx^(Nth SFN)−τ  (5)

The E-SMLC may also obtain OTDOA cell information of the serving eNodeBincluding SFN initialization time. The SFN initialization time (in secrelative to 00:00:00 on 1 Jan. 1900) may be translated to GNSS/GPSreference time. Thus, assuming that the translated SFN time isrepresented as eNB_(i) ^(SFN_init), if both eNB_(i) ^(SFN_init) andTx_eNB_(i) ^(Nth SFN) are expressed in GPS/GNSS time of day (TOD), thenthe transmission delay may be determined as provided in the relationshipbelow:δ=Tx_eNB_(i) ^(Nth SFN)−eNB_(i) ^(NFN) ^(init)   (6)

To minimize measurement errors, the location of the UE may be obtainedfrom A-GPS/A-GNSS methods by keeping the UE stationary and/or averagingthe same over a predetermined number of iterations to minimize UElocation error. Tx delay, δ, may thus be obtained by averaging overseveral times for a stationary UE location. This embodiment may also berepeated by placing UE(s) distributed over the cell area to minimize anybias from a particular location.

Thus, embodiments of the present subject matter may provide a method ofdetermining delay using a mobile device's location and a respectivesignal's propagation delay. Such delay may include cable and/or other RFcomponent delays. Further, the propagation delay may be either uplinkand/or downlink paths and may be averaged for better accuracy.

FIG. 5 is a diagram of one embodiment of the present subject matter.With reference to FIG. 5, a method 500 of determining transmission delayin a communications system is provided. At step 510, the method mayinclude receiving satellite positioning information for a mobile device.At step 520, E-CID positioning information may be received for themobile device. In some embodiments, the received E-CID positioninginformation may include timing advance information of an uplink signaltransmitted from the mobile device or timing advance information of adownlink signal received by the mobile device. In other embodiments, theE-CID positioning measurements may include timing advance type 1 ortiming advance type 2. In yet another embodiment, step 520 may includeinvoking an E-CID positioning procedure from the UP or from the CoP.

A location of the mobile device may then be determined at step 530 as afunction of the received satellite positioning information. At step 540,transmission delay between a node serving the mobile device and anantenna serving the mobile device may be determined as a function of thereceived E-CID positioning information and the determined location ofthe mobile device. In an alternative embodiment, step 540 may includedetermining cable delay and/or radio frequency component delay. In oneembodiment, the serving node is an eNodeB. In a further embodiment, themethod may include the step of determining propagation delay between theserving antenna and the mobile device as a function of the determinedmobile device location and location of the serving antenna, where thedetermined transmission delay is a function of the determinedpropagation delay. In such a method, the determined propagation delaymay be a function of a transmission path from the mobile device to theserving antenna or from the serving antenna to the mobile device. Inadditional embodiments, the method may include the step of iterativelyrepeating step 530 and averaging the determined locations over theseveral iterations. In an alternative embodiment, the method may includethe step of determining a location of one or more other mobile devicesusing respective received satellite information, whereby step 540 wouldinclude determining transmission delay as a function of the determinedlocations of the one or more other mobile devices to minimize bias fromany single location determination.

FIG. 6 is a diagram of another embodiment of the present subject matter.With reference to FIG. 6, a method 600 of determining transmission delayin a communications network having a plurality of nodes is provided. Themethod may include receiving satellite positioning information for amobile device, the received satellite positioning information includingSFN information at step 610 and receiving OTDOA measurements for amobile device from one or more of the plural nodes at step 620. In oneembodiment, step 610 includes requesting the mobile device to report aGPS to network time relationship. In another embodiment, the OTDOAmeasurements may include SFN initialization time.

A location of the mobile device may be determined as a function of thereceived satellite positioning information at step 630. At step 640, aGPS time estimate may be determined as a function of the determinedlocation of the mobile device. At step 650, transmission delay between anode serving the mobile device and an antenna serving the mobile devicemay be determined as a function of the received OTDOA measurements anddetermined GPS time estimate. In one embodiment, the serving node is aneNodeB. In a further embodiment, the method may include the step ofdetermining propagation delay between the serving antenna and the mobiledevice as a function of the determined mobile device location andlocation of the serving antenna, where the determined transmission delayis a function of the determined propagation delay. In such a method, thedetermined propagation delay may be a function of a transmission pathfrom the mobile device to the serving antenna or from the servingantenna to the mobile device. In additional embodiments, the method mayinclude the step of iteratively repeating step 630 and averaging thedetermined locations over the several iterations. In an alternativeembodiment, step 650 may include determining cable delay and/or radiofrequency component delay. In an alternative embodiment, the method mayinclude the step of determining a location of one or more other mobiledevices using respective received satellite information, whereby step650 would include determining transmission delay as a function of thedetermined locations of the one or more other mobile devices to minimizebias from any single location determination.

While the discussion above has referenced certain exemplary networkssuch as UMTS networks, the disclosure herein should not be so limited.For example, the principles discussed herein are equally applicable toother networks such as, but not limited to, a TDMA network, CDMAnetwork, a WiMax network, a WiFi network, networks utilizing EDVO, aCDMA2000 network, and 1×RTT standards or another equivalent networks orother networks that may include a system clock or equivalent. Suchexemplary system clocks may thus be utilized by embodiments of thepresent subject matter to determine timing relationships relevantherein.

The present disclosure may be implemented by a general purpose computerprogrammed in accordance with the principals discussed herein. It may beemphasized that the above-described embodiments, particularly any“preferred” or exemplary embodiments, are merely possible examples ofimplementations, merely set forth for a clear understanding of theprinciples of the present subject matter. Many variations andmodifications may be made to the above-described embodiments of thepresent subject matter without departing substantially from the spiritand principles of the present subject matter. All such modifications andvariations are intended to be included herein within the scope of thispresent subject matter.

Embodiments of the subject matter and the functional operationsdescribed herein may be implemented in digital electronic circuitry, orin computer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. Embodiments of the subject matterdescribed herein may be implemented as one or more computer programproducts, i.e., one or more modules of computer program instructionsencoded on a tangible program carrier for execution by, or to controlthe operation of, data processing apparatus. The tangible programcarrier may be a computer readable medium. The computer readable mediummay be a machine-readable storage device, a machine-readable storagesubstrate, a memory device, or a combination of one or more of them.

The term “processor” encompasses all apparatus, devices, and machinesfor processing data, including by way of example a programmableprocessor, a computer, or multiple processors or computers. Theprocessor may include, in addition to hardware, code that creates anexecution environment for the computer program in question, e.g., codethat constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, or a combination of one or moreof them.

A computer program (also known as a program, software, softwareapplication, script, or code) may be written in any form of programminglanguage, including compiled or interpreted languages, or declarative orprocedural languages, and it may be deployed in any form, including as astandalone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment. A computer program does notnecessarily correspond to a file in a file system. A program may bestored in a portion of a file that holds other programs or data (e.g.,one or more scripts stored in a markup language document), in a singlefile dedicated to the program in question, or in multiple coordinatedfiles (e.g., files that store one or more modules, sub programs, orportions of code). A computer program may be deployed to be executed onone computer or on multiple computers that are located at one site ordistributed across multiple sites and interconnected by a communicationnetwork.

The processes and logic flows described herein may be performed by oneor more programmable processors executing one or more computer programsto perform functions by operating on input data and generating output.The processes and logic flows may also be performed by, and apparatusmay also be implemented as, special purpose logic circuitry, e.g., anFPGA (field programmable gate array) or an ASIC (application specificintegrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more data memorydevices for storing instructions and data. Generally, a computer willalso include, or be operatively coupled to receive data from or transferdata to, or both, one or more mass storage devices for storing data,e.g., magnetic, magneto optical disks, or optical disks. However, acomputer need not have such devices. Moreover, a computer may beembedded in another device, e.g., a mobile telephone, a personal digitalassistant (PDA), a mobile audio or video player, a game console, aGlobal Positioning System (GPS) receiver, to name just a few.

Computer readable media suitable for storing computer programinstructions and data include all forms data memory includingnonvolatile memory, media and memory devices, including by way ofexample semiconductor memory devices, e.g., EPROM, EEPROM, and flashmemory devices; magnetic disks, e.g., internal hard disks or removabledisks; magneto optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory may be supplemented by, or incorporated in,special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described herein may be implemented on a computer having adisplay device, e.g., a CRT (cathode ray tube) or LCD (liquid crystaldisplay) monitor, for displaying information to the user and a keyboardand a pointing device, e.g., a mouse or a trackball, by which the usermay provide input to the computer. Other kinds of devices may be used toprovide for interaction with a user as well; for example, input from theuser may be received in any form, including acoustic, speech, or tactileinput.

Embodiments of the subject matter described herein may be implemented ina computing system that includes a back end component, e.g., as a dataserver, or that includes a middleware component, e.g., an applicationserver, or that includes a front end component, e.g., a client computerhaving a graphical user interface or a Web browser through which a usermay interact with an implementation of the subject matter describedherein, or any combination of one or more such back end, middleware, orfront end components. The components of the system may be interconnectedby any form or medium of digital data communication, e.g., acommunication network. Examples of communication networks include alocal area network (“LAN”) and a wide area network (“WAN”), e.g., theInternet.

The computing system may include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

While this description may contain many specifics, these should not beconstrued as limitations on the scope thereof, but rather asdescriptions of features that may be specific to particular embodiments.Certain features that have been heretofore described in the context ofseparate embodiments may also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment may also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and may even be initially claimed as such, one or morefeatures from a claimed combination may in some cases be excised fromthe combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings or figures in aparticular order, this should not be understood as requiring that suchoperations be performed in the particular order shown or in sequentialorder, or that all illustrated operations be performed, to achievedesirable results. In certain circumstances, multitasking and parallelprocessing may be advantageous. Moreover, the separation of varioussystem components in the embodiments described above should not beunderstood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemsmay generally be integrated together in a single software product orpackaged into multiple software products.

The present subject matter may thus provide a method and system fordetermining the delay in the transmission path to allow for appropriatedeployments of an exemplary OTDOA system.

As shown by the various configurations and embodiments illustrated inFIGS. 1-6, various embodiments for autonomous transmit chain delaymeasurements have been described.

While preferred embodiments of the present subject matter have beendescribed, it is to be understood that the embodiments described areillustrative only and that the scope of the invention is to be definedsolely by the appended claims when accorded a full range of equivalence,many variations and modifications naturally occurring to those of skillin the art from a perusal hereof.

We claim:
 1. A method of determining transmission delay in acommunications network having a plurality of nodes comprising the stepsof: (a) receiving satellite positioning information for a mobile device,the received satellite positioning information including System FrameNumber (SFN) information; (b) receiving observed time difference ofarrival (OTDOA) measurements for a mobile device from one or more of theplural nodes; (c) determining a location of the mobile device as afunction of the received satellite positioning information; (d)determining a Global Positioning System (GPS) time estimate as afunction of the determined location of the mobile device; and (e)determining transmission delay between a node serving the mobile deviceand an antenna serving the mobile device as a function of the receivedOTDOA measurements and determined GPS time estimate.
 2. The method ofclaim 1 wherein the step of receiving satellite positioning informationfurther comprises requesting the mobile device to report a GPS tonetwork time relationship.
 3. The method of claim 1 wherein the servingnode is an eNodeB.
 4. The method of claim 1 wherein the OTDOAmeasurements include SFN initialization time.
 5. The method of claim 1further comprising the step of determining propagation delay between theserving antenna and the mobile device as a function of the determinedmobile device location and location of the serving antenna, wherein thedetermined transmission delay is a function of the determinedpropagation delay.
 6. The method of claim 5 wherein the determinedpropagation delay is a function of a transmission path from the mobiledevice to the serving antenna or from the serving antenna to the mobiledevice.
 7. The method of claim 1 wherein the step of determiningtransmission delay further comprises determining cable delay and/orradio frequency component delay.
 8. The method of claim 1 furthercomprising the step of iteratively repeating step (c) and averaging thedetermined locations over the iteration.
 9. The method of claim 1further comprising the step of determining a location of one or moreother mobile devices using respective received satellite information,wherein the step of determining transmission delay comprises determiningtransmission delay as a function of the determined locations of the oneor more other mobile devices to minimize bias.
 10. The method of claim 1wherein the serving node is a baseband processing unit.
 11. The methodof claim 10 wherein a radio frequency front end is positioned betweenthe baseband processing unit and the serving antenna.
 12. The method ofclaim 11 wherein the step of determining transmission delay furthercomprises determining cable delay or radio frequency component delay.13. The method of claim 11 wherein the step of determining transmissiondelay further comprises determining cable delay and radio frequencycomponent delay.
 14. A communication system, comprising: a plurality ofnodes configured to provide wireless service to one or more mobiledevices; one or more processors coupled to a memory, wherein the one ormore processors are configured to: receive satellite positioninginformation for a mobile device, the received satellite positioninginformation including System Frame Number (SFN) information; receiveobserved time difference of arrival (OTDOA) measurements for the mobiledevice from one or more of the plural nodes; determine a location of themobile device as a function of the received satellite positioninginformation; determine a Global Positioning System (GPS) time estimateas a function of the determined location of the mobile device; anddetermine transmission delay between a node of the plurality of nodesserving the mobile device and an antenna serving the mobile device as afunction of the received OTDOA measurements and determined GPS timeestimate.
 15. The communication system of claim 14, wherein the one ormore processors are further configured to request the mobile device toreport a GPS to network time relationship.
 16. The communication systemof claim 14, wherein the serving node is an eNodeB.
 17. Thecommunication system of claim 14, wherein the OTDOA measurements includeSFN initialization time.
 18. The communication system of claim 17,wherein the one or more processors are further configured to determinepropagation delay between the serving antenna and the mobile device as afunction of the determined mobile device location and location of theserving antenna, wherein the determined transmission delay is a functionof the determined propagation delay.
 19. The communication system ofclaim 18, wherein the determined propagation delay is a function of atransmission path from the mobile device to the serving antenna or fromthe serving antenna to the mobile device.
 20. The communication systemof claim 14, wherein the one or more processors are configured todetermine transmission delay between the node serving the mobile deviceand the antenna serving the mobile device by determining cable delayand/or radio frequency component delay.
 21. The communication system ofclaim 14, wherein the one or more processors are further configured toiteratively repeat determining a location of the mobile device as afunction of the received satellite positioning information and averagethe determined locations over the iteration.
 22. The communicationsystem of claim 14, wherein the one or more processors are configured todetermine a location of one or more other mobile devices usingrespective received satellite information; wherein the one or moreprocessors are configured to determine transmission delay between thenode serving the mobile device and the antenna serving the mobile deviceby determining transmission delay as a function of the determinedlocations of the one or more other mobile devices to minimize bias. 23.The communication system of claim 14, wherein the serving node is abaseband processing unit.
 24. The communication system of claim 23,wherein a radio frequency front end is positioned between the basebandprocessing unit and the serving antenna.
 25. The communication system ofclaim 24, wherein the one or more processors are configured to determinetransmission delay between the node serving the mobile device and theantenna serving the mobile device by determining cable delay or radiofrequency component delay.
 26. The communication system of claim 24,wherein the one or more processors are configured to determinetransmission delay between the node serving the mobile device and theantenna serving the mobile device by determining cable delay and radiofrequency component delay.